The use of rewards (defined as anything for which an individual will work) to increase motivation is one of the most common strategies for trying to encourage cigarette smokers to quit and remain abstinent. In general, this approach is consistent with basic behavioral principles. However, recent functional brain imaging research suggests that potential rewards may be least effective at promoting smoking abstinence in the very situation they are needed most - when smokers are tempted by access to cigarettes. Specifically, smokers exhibit a significant decrease in the sensitivity of brain reward regions to nondrug (monetary) rewards when cigarettes will soon be available. Recent findings further suggest that the magnitude of this observed decrease predicts clinically relevant behavior. Thus, characterizing the effects of cigarette availability on reward sensitivity is an innovative ad significant approach to understanding vulnerability to, and prevention of, smoking relapse. In the proposed project, functional magnetic resonance imaging (fMRI) and ecological momentary assessment (EMA) methods will be integrated to address key unresolved questions about the effect of cigarette availability on sensitivity to nondrug rewards. Specifically, adult daily smokes (N = 160) will first complete laboratory sessions to measure the effects of an experimental cigarette availability manipulation on distinct phases of the neural response to nondrug (monetary) rewards using fMRI. Then, EMA will be used to measure the within- person effects of naturally time-varying perceived cigarette availability on reward sensitivity under real-world conditions over 10 days of monetarily reinforced cigarette abstinence. Our overarching hypothesis is that availability-related decreases in reward sensitivity are driven by increases in negative affect, leading to specific predictions about how neural and subjective responses to rewards will be altered. These predictions will be tested across three specific aims: 1) To examine the effect of cigarette availability on neural activity during anticipation and receipt of rewards; 2) To examine the effect of cigarette availability on subjective responses to rewards in daily life; and 3) To determine whether the effect of cigarette availability on neural responses to rewards predicts subsequent reward-related behavior outside of the laboratory. Results from the project will advance basic knowledge regarding the effect of perceived cigarette availability on neural and subjective responses to nondrug rewards in the laboratory and in daily life. This knowledge, in turn, will inform the development and implementation of novel approaches to reduce the negative impact of cigarette availability on reward functioning (e.g., ecological momentary interventions dynamically tailored to the person and situation).